Process for adherent metallizing of synthetic resins

ABSTRACT

Synthetic resins having adherent electrically conductive metal coatings on their surfaces are produced by preparing the synthetic resin A to be metallized by incorporating therein (1) a polymeric material having a relatively low softening temperature range and which is capable of being attacked oxidatively by the usual conditioning baths, such as, chromosulfuric acid, and (2) a finely divided filler which is capable of binding the catalyst required through functional groups and effecting chemical metallization of the thus prepared combination.

llniieel States Patent [72] lnventors Helmut Knorre Hainstadt/Main;Gunter Relff, Kleinosthein, both of Germany [21] Appl. No. 753,780 [22]Filed Aug. 19, 1968 [45] Patented Dec. 14, 1971 [73] Assignee DeutscheGoldund Silber-Scheideanstalt Vormals Roessler Frankfurt/Main, Germany[32] Priority Aug. 18, 1967 [33] Germany [31] P1621232.1

[54] PROCESS FOR ADHERENT METALLIZING OF SYNTHETIC RESINS 10 Claims, NoDrawings [52] U.S. Cl 117/213, 117/47 A, 117/160, 117/l38.8, 117/227,204/30, 156/2 [51] Int. Cl B44d l/40, C23b 5/62 [50] Field of Search204/30; 117/213, 138.8 E, 138.8 F, 138.8 G, 138.8 J, 47 A; 156/2 [56]References Cited UNITED STATES PATENTS 3,546,009 12/1970 Schneble et a1117/212 3,560,257 2/1971 Schneble et a1 117/212 3,146,125 8/1964Schneble et al... 117/213 3,399,268 8/1968 Schneble et al... 117/2133,466,232 9/1969 Francis et a1. 156/2 3,416,992 12/1968 Amos 117/2133,259,559 7/1966 Schneble etal 117/212 3,269,861 8/1966 Schneble et al117/212 3,347,724 10/1967 Schneble et al... 117/47 3,370,974 2/1968Hepfer 1 17/47 3,245,826 4/1966 Luis et a1. 117/67 2,690,401 9/1954Gutzert et al.. 117/160 2,454,610 11/1948 Narcus 117/35 3,305,460 2/1967Lacy 117/47 Primary ExaminerWilliam D. Martin Assistant ExaminerM.Sofocleous Attorneys-Francis D. Stephens and Hugo Huettig, Jr.

ABSTRACT: Synthetic resins having adherent electrically conductive metalcoatings on their surfaces are produced by preparing the synthetic resinA to be metallized by incorporating therein (1) a polymeric materialhaving a relatively low softening temperature range and which is capableof being attacked oxidatively by the usual conditioning baths, such as,chromosulfuric acid, and (2) a finely divided filler which is capable ofbinding the catalyst required through functional groups and effectingchemical metallization of the thus prepared combination.

PROCESS FOR ADI-IERENT METALLIZING OF SYNTHETIC RESINS RELATEDAPPLICATIONS The copending applications of Kallrath et al., Ser. No.593,736, filed Nov. 14, 1966, and now abandoned and Knorre et al., Ser.No. 719,017, filed Apr. 5, 1968, now US. Pat. No. 3,546,01 l, arerelated to the present application and the disclosure thereof areincorporated by reference in the present application.

BACKGROUND OF THE INVENTION The application relates to a process for theadherent metallizing of synthetic resins, especially, upon partsproduced by injection molding or extrusion, by the nonelectrolyticdeposition of an electrically conductive metallic layer from apredominantly aqueous metal salt solution containing a reducing agent inthe presence of metals catalyzing the deposit of metals in which thebase for anchoring the adherent metal coating is provided by a specialpretreatment.

A number of processes are already known which render it possible to cladpractically any desired synthetic resin with a metal coating. The bestknown are the vacuum coating method in which a metal coating isdeposited from metal vapors under high vacuum and the chemical reductivedeposition of metals from solutions. In most instances, however, thecoatings deposited are not very adherent so that the use of the articlesmetallized thereby is more or less limited to decorative purposes.Nevertheless, there has been no lack of attempts to find ways to provideadherent metal coatings on synthetic resins.

For example, a process has become known in DAS US. Pat. No. 1,225,940for the vacuum deposition of an adherent metal coating on a base ofhalogenated polyethylene in which an anchoring intermediate metal oxidecoating is provided by cathode sputtering. This special process, just asthe vacuum coating process, in itself is very costly and in view of thehigh vacuum techniques required is necessarily limited with regard todimensions.

As a result the art turned to other more economical processes forproducing adherent metal coatings, among which the nonelectrolyticdeposit of metals coatings on certain types of ABS(acrylonitrile-butadiene-styrene) resins has particularly become known.In such process the adherent anchoring of a metal coating obtained byreductive chemical deposition is attained by a chemical pretreatment ofthe synthetic resin part to be metallized to efiect a roughening of itssurface. Such process, however, has the following disadvantage: It islimited in its application to a very definite synthetic resin type whichvery greatly limits the synthetic resin properties which in turn limitsthe field of application of the metallized parts which are produced.Furthermore, the capability of this type of synthetic resin of beingmetallized and the adherence of the metal coatings produced depends to agreat extent upon the synthesis and the further processing (extrusiontemperature and velocity), as well as the corresponding pretreatmentsresulting therefrom.

According to another proposal (US. application Ser. No. 593,736)adherent metal coatings can be produced on synthetic resins, which arenot limited to any particular resin types, but also in addition avoidthe disadvantages of the pretreatment of the ABS resin types mentionedabove. According to this process, the synthetic resin is prepared with afiller which, on one hand, is capable of chemically binding thecatalysts required through functional groups and, on the other hand,efiects the necessary surface roughness after a pretreatment of thefilled synthetic resin with chromosulfuric acid and aqueous NaOI-l.

It was, however, found that this process can only be carried out withgood success with pressed plates, whereas difficulties are encounteredwith parts which are produced at present by the usual more rationalprocesses, such as, injection molding or extrusion. Good metallizationand adherence could only be attained with injection molded or extrudedparts of the synthetic resins prepared with the fillers as describedabove if very high degrees of filling are used or if the pretreatmentwhich with chromosulfuric acid and NaOH was extended to an extremelylong period. Both, however, preclude a practical metallizing process.Normally with inclusions of increased quantities of fillers theincorporation of such filler in the resin and the thermoplasticprocessing of the filled resin are rendered more difficult. In addition,in some instances undesirable changes in the properties occur. The usualmethods for incorporating larger quantities of fillers in this instancecannot be used as they either cause an undesirable change in theproperties of the synthetic resins and/or they are unsuited formetallization. On the other hand, the long times required forpretreatment are not practical in metallizing processes as the times ofthe various steps must be uniformly adjusted with respect to each otherand be relatively short in automatic metallizing and, on the other hand,there is the danger of damage to the synthetic resin.

DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS It is theobject of the invention to provide a process for adherent metallizing ofsynthetic resins by the nonelectrolytic deposit of an electricallyconductive metal coating from an aqueous metal salt solution containinga reducing agent in the presence of metals catalyzing such deposit whichrenders it possible to provide adherent metal coatings on syntheticresin articles produced by usual presently used economical processingmethods, such as, injection molding or extrusion. According to theinvention this object is attained by incorporating a filler (B) which iscapable of binding the catalyst required for the metallizing throughfunctional groups and which also effects the necessary roughening of thesurface for the anchoring of an adherent metal coating of the syntheticresin composition to be metallized and one or more polymers orcopolymers or mixtures thereof(C) which have a relatively low softeningrange, preferably, from 30 to l00 C., and which are attacked oxidativelyin the usual conditioning baths used for metallizing, preferably,chromosulfuric acid and/or are capable of forming functional groups,such as, for example, hydroxyl, carboxyl, or sulfonic acid groups by asuitable pretreatment, into the synthetic resin base (A) which is to bemetallized and subsequently metallizing the thus prepared syntheticresin in a known way by a chemical metallizing procedure and, ifdesired, galvanically depositing a metallic coating on the thusmetallized resin.

The following requirements must be met in the combination ofsyntheticresin (A) plus filler (B) plus polymer (C):

The polymer (C) which is added to synthetic resin (A) must be compatibletherewith and should ease the working in of larger and/or veryvoluminous quantities of filler into the synthetic resin (A).Furthermore, good processing properties of the synthetic resincombination which permit processing on usual processing apparatus, theability to form unobjectionable surfaces, and a rational and firmlyadherent metallizing should be assured.

These requirements are fulfilled in an almost ideal manner by thecombination according to the invention as in the pretreatment of thesynthetic resin combination in conditioning baths such combinationprovides for a change in the surface characteristics so that theadherent metallization rendered possible by the added filler can becarried out in a rational manner. The incorporation of polymers,copolymers or their mixture (C) by themselves into an unfilled syntheticresin (A) only provides for inconsequential improvements with regard toadherent metallization. To the contrary, their addition without additionof filler renders the metallizing process more difficult in view offactors of uncertainty occurring in the pretreatment and furthermorethey also impair certain physical properties of the metallized productwhich are important for their use. Unexpectedly, however, they assistthe activating process without sensitization with stannous chloride orother reducing agents.

As the sensitization step as well as the apparatus therefore are notrequired, it is possible to omit the normally necessary transfer of thesynthetic resin parts to supports which are not wetted with stannouschloride. in addition, in the process according to the invention only asmuch activator as is actually necessary is deposited on the surface ofthe synthetic resin; this signifies that the metallization cannot beinjured by under or over activation and as a consequence faultymetallization can be prevented to a far reaching degree. In addition,significant advantages are attained by the omission of thesensitization, for instance, in the printed circuits in which above allthe presence of stannous chloride is disturbing when contacts are madebetween conductive circuits.

The addition of the polymers, copolymers and/or mixtures thereof (C)according to the invention facilitate the incorporation of largerquantities of fillers (B) in the synthetic resin (A) and the processingof such filled resins (ABC) to parts ready for metallization in thatthey increase the ability of the resin to take up fillers and at thesame time improve the poor flow characteristics normally caused by theincorporation of larger quantities of fillers so that they approximatethose of the unfilled resins. This also renders it possible to attainsufficiently smooth surfaces such as are desired for the metallizationand use of the parts produced.

Polymers, copolymers or mixtures thereof which have a relatively lowsoftening range, preferably, of from 30 to 100 C., and which have therequisite compatibility with synthetic resin (A) which is to bemetallized and in addition can be attacked oxidatively in the usualconditioning baths, such as, chromosulfuric acid, and/or can formfunctional groups, such as, hydroxyl, carboxy or sulfonic acid groups bya suitable pretreatment or which already possess functional groups, haveproved especially suited for the process according to the invention.Depending upon the type of polymer (C), the filler (B) and the resin (A)to be metallized and the use to which the metallized object is to beput, the additions of the polymer (C) should lie in the order of l to 40wt. percent, preferably, 5 to percent, with reference to the weight ofsynthetic resin Examples of such metallizing promoting polymer additions(C), for instance, are polyvinyl acetate, polyisobutylene, copolymers ofethylene, propylene and higher olefins, as well as vinyl chloride withvinyl acetate, isobutylene, acrylic acid esters, methacrylic acidesters, butadiene and acrylonitrile or corresponding polymer mixtures ofpolyethylene, polypropylene, higher olefins and polyvinyl chloride withpolyvinyl acetate, polyisobutylene, poly acrylic acid esters,polymethacrylic acid esters and polyacrylonitrile.

The additions according to the invention (BC) are expedientlyincorporated into synthetic resin (A) by first forming a mixture of thefiller (B) which is suited for the metallization with the metallizationpromoting polymers, copolymers or polymer mixtures (C) and then workingsuch mixture into the resin (A). However, it also is possible first tomix the resin (A) with polymeric material (C) and then working thefiller (B) into such mixture. Instead of mixtures of the resin (A) to bemetallized with the polymeric materials (C) which promote metallizationand fillers (B), it is also possible to form the composition accordingto the invention to be metallized from copolymers of resin (A) withpolymeric material (C) and the filler (B). It also is possible tocross-link synthetic resin (A) and/or the polymeric material (C).

Inorganic finely divided substances with a secondary particle sizebetween 0.1 and 150p., preferably, between 0.2 and which containhydroxyl groups or are capable of having such hydroxyl groups formedtherein by suitable pretreatment so that, for example, Ag** or Pd"***ions can be chemically bound from an ammonical solution, have been foundparticularly suited as fillers promoting metallization. Wet precipitatedor pyrogenic metal or metalloid oxides, such as silica, titaniumdioxide, alumina in the form of single oxides,

mixtures of such oxides, so-called mixed oxides (in which each primaryparticle already consists of a mixture of the oxides) or co-coagulateswherein the secondary particles are formed by co-coagulation ofseparately formed primary particles or different oxides have, forexample, been found suited.

The metallizing process according to the invention is especiallypractical when alkali metal and/or alkaline earth metal and/oralumo-silicates, which do not require a treatment with aqueous NaOH toeffect a corresponding conditioning of the resin surfaces, are used asthe fillers. Synthetic resins produced with the last-mentioned fillersonly need be given a pretreatment with the conventional chromosulfuricacid baths in order that they be degreased, hydrophilized andconditioned simultaneously. This renders it possible in practice to usethe same apparatus for metallizing ABS resins and for metallizing thecombinations (ABC) according to the invention.

In general, in carrying out the process according to the invention, thesynthetic resin (A) which is to be metallized is mixed, in the form of agranulate or powder as normally used in synthetic resin processing, withcorresponding portions of the polymeric material (C) and with filler(B), for instance, in a weight proportion of 70zl0z20. To effect furtherhomogenization and/or plastification such mixture is, for example,treated in a heated punch kneader or on mixing rolls or in an extruder,preferably, at temperatures between and 200 C. Before processing thesemifinished or finished parts, this mixture is expediently formed intogranules or agglomerates. The semifinished or finished parts produced onusual processing machines can then be metallized in the followingprocessing operation.

After treatment in hot chromosulfuric acid (about 60 C.) the syntheticresin parts are activated in an ammoniacal silver nitrate bath andsubsequently provided with an electrically conductive metal layer in aconventional chemical metallizing bath, preferably, a chemical copperplating bath. The metal layer then, if desired, can be thickened inconventional galvanic baths and, depending upon the intended use,covered with decorative covering layers such as bright copper, brightnickel, bright chromium and the like.

In order to test the adhesive strength of the coating obtained in thechemically metallized samples, the coating can be thickened in agalvanic copper plating bath to a thickness of 10011. and the samplesthen be subjected to the peeling test according to DIN 40802. Thesynthetic resins which have been metallized using the process accordingto the invention always gave values which were far above the minimumvalue of 0.9 kg./cm. required for metallized ABS synthetic resins. Theoptimal values obtained with the synthetic resins prepared according tothe invention as described above are up to around 5 kg./cm. and when anadditional preconditioning bath of aqueous NaOH was employed adhesivestrengths of up to about 6 kg./cm. can be obtained. The adhesivestrength increases with increasing degree of filling. 5 wt. percent offiller in homogeneous distribution in the resin is considered theminimum degree of filling. The quantity of filler employed can, forexample, be between 5 and 70 wt. percent and preferably is between about5 and 30 wt. percent with reference to synthetic resin (A).

The adhesive strength in addition is dependent upon the duration of theconditioning in the chromosulfuric acid and this again is dependent uponthe quantity and type of the metallization promoting polymeric material(C) which is added. For example, with a 10 percent addition of acopolymer of ethylene and vinyl acetate to poiyolefins (A) optimumadhesive strength values are obtained with conditioning periods of 5-15minutes in chromosulfuric acid. The chromium VI content of the sulfuricacid should not be under 5 percent CrO lliter and preferably should bebetween 7 and 20 percent CrO /liter. An addition of phosphoric acid tothe chromosulfuric acid is not necessary in the process according to theinvention, but such addition is not disturbing.

it has also been found that the adhesive strength of the metal coatingsproduced according to the invention after being subjected to repeatedcycles of hot and cold, for example, between +120 and 40 C. when thesynthetic resin base (A) is polyethylene, is not substantially impaired.

The process according to the invention is applicable for themetallization of all synthetic resins (A) a. which are stable againstthe etches, such as, chromosulfuric acid, or leaches, such as, aqueousNaOH which are required for conditioning of the surface and are not oronly immaterially attacked thereby (excepting the hydrophobization ofthe synthetic resin surface) b. which in combination with the polymericmaterial (C) can be prepared homogeneously or superficially with 5-40percent of the fillers (B) according to the invention c. which arecompatible with polymeric materials (C) and fillers (B) to give a solid,injection moldable and/or'extrudable and/or compression moldablemixture.

Illustrative examples of such synthetic resins (A), for example, arethermoplastic resins, such as, polyolefins, such as polyethylene andpolypropylene, polyvinyl chloride, polyformaldehyde, ABS resins andduroplastic resins, such as, phenol aldehyde and epoxy resin.

The treatment employed according to the invention to introduce thehydroxyl groups into the finely divided fillers employed according tothe invention, if they are not already present therein, such as, forinstance, when finely divided car bonates or natural minerals, such as,corundum, natural silicates, as well as other finely divided naturalminerals, can, for example, be with hot aqueous NaOH.

The following examples will serve to illustrate the invention.

EXAMPLE l The following synthetic resin-filler mixtures were produced ina punch kneader:

a. polypropylene (A) with 20 percent of wet precipitated silica (B)(with 6 percent silanol groups and a secondary particle size of 15;i)

b. polypropylene (A) with 20 percent calcium silicate (B) (72 percentSiO percent CaO, 6 percent silanol groups, secondary particle size 10p.)

c. polypropylene (A) with 8 percent ethylene-vinyl acetate copolymer (C)(about percent vinyl acetate) and percent precipitated silica as under(a) d. polypropylene (A) with 8 percent ethylene-vinyl acetate copolymer(C) (about 15 percent vinyl acetate) and 20 percent calcium silicate asunder (b) e. polypropylene (A) with 8 percent ethylene-vinyl acetatecopolymer (C) (about 15 percent vinyl acetate) without filler.

The mixtures were then granulated with an extruder and subsequentlyextruded to form plates. Both during the working in of the filler andduring the subsequent processing of the filled synthetic resin mixtures,mixtures (c) and ((1) exhibited significantly improved processingproperties and a more favorable (smoother) surface formation whencompared with mixtures (a) and (b).

A plate from each of the mixtures (a) through (c) and a plate of purepolypropylene were placed on a support and dipped for 5 minutes in 60 C.chromosulfuric acid bath (about 7 percent CrO /liter) and rinsedthereafter for 15 minutes in hot tap water and then dipped for 15minutes in an ammoniacal silver nitrate solution (2.0 g. AgNO /liter)and then after repeated rinsing with water introduced into a chemicalcopper plating bath (7 g. CuSO.,-l-1 O, 34 g. Rochelle salt, 10 g. NaOH,6 g. Na CO and 100 ml. formaldehyde (40 percent per liter of aqueousbath with a bath load of 2 dmF/liter). All plates except that of purepropylene received a thin copper coating which was increased to a100,41. thick coating in a conventional galvanic copper plating bath(250 g./liter Cu SO -l-l 0), 50 g./liter cc. H 50 0.1 g./liter wettingagent; 0.5 to 2.0 A./dm. After such galvanic treatment to increase thethickness of the copper coating, the coated samples were rinsed anddried for 25 hours in air and 24 hours in a drying cupboard at 50 C. andthen subjected to the peeling test to determine the adhesive strength ofthe coatings obtained. The results were as follows:

(a) 0.3 kg./cm., (b) 0.2 kg./cm., (c) 3.2 kg./cm., (d) 4.2 kg./cm. and(e) 0.7 kg./cm.

EXAMPLE 2 Powdered polyethylene (A) was mixed in a fluid mixer with thesubstances or substance mixtures indicated in the followmg:

a. polyethylene (A) with 10 percent of wet precipitated silica (B) (with6 percent silanol groups, secondary particle size /0 b. polyethylene (A)with 10 percent calcined silica (B) (secondary particle size 3-l0p.)

c. polyethylene (A) with 15 percent of sodium aluminum silicate (B) (72percent SiO;, 8 percent A1 0 7 percent Na O, secondary particles size4p.)

(d) through (f) as in (a) through (c) but with an additional 10 percentof polyisobutylene (C) (softening range 5070 C.).

The mixtures were granulated with an extruder and processed to plateshaped samples by injection molding. A plate of each of mixtures (a)through (f) and a plate of pure polyethylene were pretreated, metallizedand tested for adhesive strength as in example 1. Again the purepolyethylene plate could not be metallized. The following adhesivestrengths were attained:

(a) only metallized in spots, no adherence, (b) 0.2 kg./cm., (c) 0.3kg./cm., (d) 1.6 kg./cm., (e) 2.1 kg./cm., (f) 3.15 kg./cm.

EXAMPLE 3 Samples of plates as in example 2 were again metallized asdescribed in such example except that after the chromosulfuric acidtreatment they also were given a treatment at 60 C. in aqueous 30percent NaOl-l for 15 minutes. In this instance the following adhesivestrengths were obtained:

(a) 0.4 kg./cm., (b) 0.5 kg./cm., (c) 0.35 kg./cm., (d) 1.8 kg./cm., (e)4.2 kg./cm. and (f) 5.9 kg./cm. In this instance also the purepolyethylene plate could not be metallized.

The concentration of the aqueous NaOH conditioning baths which can beused according to the invention for the additional conditioning of thefiller containing synthetic resin compositions can, for example, bebetween 40 and 400 g./l., preferably, about 300 g./l.

Additional illustrative examples of suitable polymeric material (C), forinstance, are:

a. copolymers of ethylene and vinyl acetate with a softening range of7090 C.

b. copolymers of ethylene and ethyl methacrylate with a softening rangeof -90 C.

c. copolymers of ethylene and methyl acrylate with a softening range of70-90 C.

d. polymer mixtures of polyisobutylene and polyethylene with a softeningrange of 65-80 C.

We claim:

1. In the method of electrolessly applying an adhering electricalconducting metal layer to the surface of a shaped synthetic resinsubstrate article, said article having been shaped by a priorfabrication, degreasing, hydrophilizing and conditioning the surface ofsaid synthetic resin substrate article with a cleaning and conditioningliquid, exposing the degreased surface to a metal activating solutionuntil the surface of said resin substrate article has become modifiedwherein said activating metal is selected from the group consisting ofsilver, palladium and mixtures thereof, and electrolessly depositing anelectrically conducting metal on said activated surface the improvementwhich comprises forming said synthetic resin substrate article from amixture consisting of (A) synthetic polyolefm resin, (B) a finelydivided filler comprising an inorganic material containing functionalhydroxyl groups capable of binding said activator metal and having asecondary particle size of between 0.1 and 150p. and (C) a syntheticresin other than said resin (A) but compatible therewith and with saidfiller (B) having a softening range between about 30l00 C. and which iscapable of being oxidatively attacked by said cleaning and conditioningliquid, wherein said synthetic resin (C) is present in an amount of 1-40weight percent referred to said synthetic resin (A) and said filler (B)is present in an amount of 5 to 70 weight percent referred to saidsynthetic resin (A).

2. Method according to claim 1 wherein said synthetic resin (C) isselected from the group consisting of polyvinyl acetate,polyisobutylene, copolymers of olefins and copolymers of vinyl chloridewith vinyl acetate, isobutylene, acrylic acid esters, methacrylic acidesters, butadiene and acrylonitrile and polymer mixtures of polyolefinsand of polyvinyl chloride with polyvinyl acetate, polyisobutylene,polyacrylic acid esters and polyacrylonitrile.

3. Method according to claim 1 wherein said synthetic resin (C) ispresent in an amount of 5-15 weight percent referred to said syntheticresin (A).

4. Method according to claim 1 wherein said filler (B) is at least onemember selected from the group consisting of alkali metal-, alkalineearth metaland alumo-silicates.

5. Method according to claim 1 wherein said filler (B) is present in anamount of 5 to 30 weight percent referred to said synthetic resin (A).

6. Method according to claim 1 wherein said synthetic resin (C) containsfunctional groups selected from hydroxyl, carboxyl and sulfonic acidgroups.

7. Method according to claim I wherein said filler (B) is a finelydivided inorganic material having a secondary particle size of between0.2 and 30p.

8. Method according to claim 1 wherein said filler (B) is a metal oxide,a metalloid oxide or a mixture thereof.

9. Method according to claim 1 wherein the tiller is a wetprecipitatedor pyrogenic silica, titanium dioxide, alumina, mixture of such oxides,co-oxides formed by said oxides or coagulate formed by said oxides.

10. Method according to claim 1 wherein said electric conducting metalis copper.

l t t F

2. Method according to claim 1 wherein said synthetic resin (C) isselected from the group consisting of polyvinyl acetate,polyisobutylene, copolymers of olefins and copolymers of vinyl chloridewith vinyl acetate, isobutylene, acrylic acid esters, methacrylic acidesters, butadiene and acrylonitrile and polymer mixtureS of polyolefinsand of polyvinyl chloride with polyvinyl acetate, polyisobutylene,polyacrylic acid esters and polyacrylonitrile.
 3. Method according toclaim 1 wherein said synthetic resin (C) is present in an amount of 5-15 weight percent referred to said synthetic resin (A).
 4. Methodaccording to claim 1 wherein said filler (B) is at least one memberselected from the group consisting of alkali metal-, alkaline earthmetal- and alumo-silicates.
 5. Method according to claim 1 wherein saidfiller (B) is present in an amount of 5 to 30 weight percent referred tosaid synthetic resin (A).
 6. Method according to claim 1 wherein saidsynthetic resin (C) contains functional groups selected from hydroxyl,carboxyl and sulfonic acid groups.
 7. Method according to claim 1wherein said filler (B) is a finely divided inorganic material having asecondary particle size of between 0.2 and 30 Mu .
 8. Method accordingto claim 1 wherein said filler (B) is a metal oxide, a metalloid oxideor a mixture thereof.
 9. Method according to claim 1 wherein the filleris a wet-precipitated or pyrogenic silica, titanium dioxide, alumina,mixture of such oxides, co-oxides formed by said oxides or coagulateformed by said oxides.
 10. Method according to claim 1 wherein saidelectric conducting metal is copper.